# std::move_only_function::operator=

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< cpp‎ | utility‎ | functional‎ | move only function

move_only_function& operator=( move_only_function&& other ); | (1) | (since C++23)
move_only_function& operator=( const move_only_function& ) = delete; | (2) | (since C++23)
move_only_function& operator=( std::nullptr_t ) noexcept; | (3) | (since C++23)
template< class F > move_only_function& operator=( F&& f ); | (4) | (since C++23)

Assigns a new target to `std::move_only_function` or destroys its target.

1) Moves the target of other to *this or destroys the target of *this (if any) if other is empty, by auto(std::move(other)).swap(*this). other is in a valid state with an unspecified value after move assignment.
2) Copy assignment operator is deleted. `std::move_only_function` does not satisfy CopyAssignable.
3) Destroys the current target if it exists. *this is empty after the call.
4) Sets the target of *this to the callable f, or destroys the current target if f is a null function pointer, a null pointer to member function, or an empty `std::move_only_function`, as if by executing move_only_function(std::forward<F>(f)).swap(*this);. This overload participates in overload resolution only if the constructor of `move_only_function` from `F` participates in overload resolution. The program is ill-formed or has undefined behavior if the selected constructor call is ill-formed or has undefined behavior.

### Parameters

other | - | another `std::move_only_function` object to move the target of
f | - | a callable object to initialize the new target with

### Return value

*this

### Notes

It is intentional not to require the move assignment operator to be noexcept to leave room for an allocator-aware `move_only_function` in future.

`move_only_function` can be assigned from std::in_place_type<Fn> given it can be constructed from that argument.

### Example

| This section is incomplete Reason: no example

### See also

operator= | assigns a new target (public member function of `std::function<R(Args...)>`)

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